Pacquiao, who defeated Miguel Cotto last month to win seven world boxing titles in seven different weight classes, was accompanied by his wife, Jinkee, and mother, Dionisia, in filing his candidacy in southern Sarangani province's Alabel township.
He was defeated in 2007 when he ran for the congressional seat in of nearby General Santos city, where he began his boxing career.
A former baker and construction worker born to a poor family, Pacquiao became an embodiment of a rags-to-riches story in the country where one-third of the 90 million people live on less than $1 a day.
Pacquiao told The Associated Press in March he wanted to serve the many poor people in his province.
"I want to help them because I know what they feel right now. It is not easy to help other people. That is a big responsibility. I will focus on that for the meantime," he told AP.
It wasn't immediately clear if he will still fight Floyd Mayweather Jr. if he wins in congress.
Supporters cheered as he released white balloons and showed them his certificate as the lead candidate of his party, the People's Champ Movement, outside the Commission on Elections office in Alabel, about 620 miles (1,000 kilometers) south of Manila.
